Lens specs of smartphones for camera tracking in Blender
For proper tracking you don't necessarily have to know the sensor dimensions or lens size. What matters is to determine the field of view or angle of coverage for your particular camera.

That value can then be applied to any combination of sensor size and lens sizes.

One way to get a good estimate of your camera's field of view it is to shoot video of an object of known dimensions, for example: a wall that you know is 4 meters wide. Using your camera, walk to the point where the wall fits perfectly in the frame. Then measure the distance from the wall to the camera (2 meters in this particular example).

In blender create a solid that reproduces your wall and place camera at the measured distance from the wall.



On the camera lens settings move the Focal Length numbers until you can see the wall filling the frame.



You can then use those values (lens and sensor size) for your track. The perspective of your real camera and Blender's should match very closely for tracking purposes.

(for even more accuracy don't forget to calculate the distortion for your lens. See: https://blender.stackexchange.com/a/15622/1853)